Reference range determination for imaging biomarkers: Myocardial T1.

BACKGROUND: Imaging biomarkers, such as the T1 relaxation time of the myocardium using MRI, can be valuable in cardiac medicine if they are properly validated. Consensus statements recommend that for myocardial T1 , each investigator should establish a reference range. PURPOSE: To describe a statistically valid method for determining and reporting the reference range in each center, which simultaneously minimizes the twin risks of undersampling, leading to a uselessly uncertain range, and oversampling, which exposes volunteers to unnecessary scanning and wastes resources. STUDY TYPE: Cohort. POPULATION: In all, 278 normal human subjects without cardiac disease from two cardiac MR centers. FIELD STRENGTH/SEQUENCE: 1.5 T and 3 T; Modified Look-Locker Inversion recovery sequence. ASSESSMENT: The T1 relaxation time was estimated from multiple samples of tissue magnetization after inversion. A valid method for calculating a reference range was used. STATISTICAL TESTS: Shapiro-Wilk test for normality; Tukey robust approach for identification of outliers; reference range calculation with confidence intervals. RESULTS: Reference ranges for measurement of myocardial T1 were calculated, with confidence intervals, enabling comparison with clinically important differences. At 3 T: 1129 to 1301 msec at site 1 (n = 21) and 1160 to 1309 msec at site 2 (n = 59), and at 1.5 T at site 2: 933 to 1020 msec (male, n = 130) and 965 to 1054 msec (female, n = 68). The 3 T reference range from site 1 was successfully benchmarked against the 3 T reference range at site 2. DATA CONCLUSION: Myocardial T1 reference ranges can be properly characterized, enabling clinical comparison to a valid reference range with known confidence intervals, using methodology similar to that described in this report. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:771-778.

Diagnostic accuracy of cardiac magnetic resonance imaging in the detection and characterization of left atrial catheter ablation lesions: a multicenter experience.

INTRODUCTION: We tested the hypothesis that cardiovascular magnetic resonance (CMR) imaging can reliably distinguish the presence or absence of left atrial (LA) ablation lesions by blinded analysis of pre- and postablation imaging. METHODS: Consecutive patients at 2 centers undergoing pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation by either wide area circumferential radiofrequency ablation (WACA) or ostial ablation with a cryoballoon underwent CMR late gadolinium enhancement (LGE) imaging pre- and 3 months postablation. Imaging was anonymized for blinded analysis of (1) LGE images, and (2) a 3D fusion image with LGE projected onto a segmented LA surface. Scans were categorized using both assessment techniques separately as pre- or postablation, and if postablation, whether lesions were in an ostial or WACA distribution. RESULTS: LGE imaging was performed in 50 patients (aged 60 ± 10 years, 68% male, 24 underwent WACA and 26 had cryoablation). Sensitivity and specificity for detection of ablation lesions was 60% and 96% on LGE imaging. Sensitivity was higher using 3D fusion imaging (88%; P = 0.003). The proportion in whom lesions were both detected and the distribution correctly assessed as WACA or ostial was higher with 3D fusion imaging compared to LGE imaging (54% vs 28%; P = 0.014). There was no difference in the detection of radiofrequency ablation lesions compared to cryoablation lesions (58% vs 62%; P = 1.000). CONCLUSION: LGE imaging of atrial scar is not yet sufficiently accurate to reliably identify ablation lesions or to determine lesion distribution.

Resolution of Behçet's syndrome associated pulmonary arterial aneurysms with infliximab.

INTRODUCTION: We describe the successful treatment of pulmonary arterial aneurysms in Behçet's syndrome using a tumor necrosis factor (TNF) inhibitor. METHODS: A case is reported of Behçet's syndrome complicated by pulmonary arterial aneurysms that responded to anti-TNF therapy. This is accompanied by a literature review of previously published cases. We searched the English language medical literature using the PubMed and Medline search terms: "Behçet's," "Pulmonary aneurysms," and "infliximab," "etanercept," or "adalimumab." RESULTS: A 43-year-old man with a 6-month history of oral and genital ulcers, weight loss, and fatigue developed arterial aneurysms in the common carotid and common iliac arteries and thromboses in a femoral vein and pulmonary arteries. Treatment with high-dose oral corticosteroids and pulsed intravenous cyclophosphamide was initiated but while on treatment he developed pulmonary arterial aneurysms with hemoptysis. His treatment was changed to intravenous infliximab with methotrexate to which he showed a good response with marked clinical improvement, reduction in his inflammatory markers, and regression of the pulmonary arterial aneurysms. The review of the literature identified 3 reported cases of treatment of pulmonary arterial aneurysms in Behçet's syndrome with anti-TNF therapy, with good outcomes in each case. CONCLUSIONS: Pulmonary artery aneurysms are important complications of Behçet's syndrome. Anti-TNF inhibitors should be considered in patients who do not respond to treatment with corticosteroids and cyclophosphamide.

CT evaluation of pulmonary venous anatomy variation in patients undergoing catheter ablation for atrial fibrillation.

To characterize pulmonary vein (PV) anatomy and the relative position of the PV ostia to the adjacent thoracic vertebral bodies, two readers reviewed 176 computed tomography pulmonary venous studies. PV ostial dimensions were measured and PV ovality assessed. Anatomical variations in PV drainage were noted. The position of the PV ostium relative to the nearest vertebral body edge was recorded. Right PV ostia were significantly more circular than the left (p<.001). Anatomical variability was greater for right PVs: 82% of patients had 2 ostia, 17% had 3 ostia, 0.5% had 4 ostia and 0.5% a common ostium. For left PVs, 91% of patients had 2 ostia, 8.5% a common ostium and 0.5% 3 ostia. Mean ostial distances from vertebral margin were: right PVs 3.62±7.48 mm; left PVs 3.84±8.46 mm (p=.72). 65% of right upper PV, 60.5% of right lower PV, 51% of left upper PV and 57% of left lower PV ostia were positioned lateral to vertebral bodies. Right PV ostia are rounder than left-sided and right PV drainage is more variable. As a significant proportion of PV ostia overlap the vertebral bodies, prior anatomical evaluation by CT can assist catheter ablation procedures for atrial fibrillation (AF), especially when performed under fluoroscopy.

Aortic remodelling in Fabry disease.

AIMS: To evaluate thoracic aortic dilation in patients with Fabry disease (FD). METHODS AND RESULTS: A cohort of 106 patients with FD (52 males; 54 females) from three European centres were studied. The diameter of the thoracic aorta was assessed at three levels (sinus of Valsalva, ascending aorta, and descending aorta) using echocardiograms and cardiovascular magnetic resonance imaging. Aortic dilation at the sinus of Valsalva was found in 32.7% of males and 5.6% of females; aneurysms were present in 9.6% of males and 1.9% of females. No aortic dilation was observed in the descending aorta. There was no correlation between aortic diameter at the sinus of Valsalva and cardiovascular risk factors. CONCLUSION: Fabry disease should be considered as a cardiovascular disease that affects the heart and arterial vasculature, including the thoracic aorta. Thus, patients with FD should be closely monitored for the presence, and possible progression and complications of aortic dilation. CLINICAL TRIAL REGISTRATION: Protocol 101/01. Ethics committee, Faculty of Medicine, Lausanne.

A rare combination of cardiopulmonary anomalies demonstrated on ventilation-perfusion scan.

In this case report we describe an unusual appearance seen on a ventilation-perfusion (V/Q) scan in a woman with pulmonary hypertension. Although the pulmonary hypertension was not caused by pulmonary emboli, the V/Q scan suggested several cardiac anomalies which may lead to pulmonary hypertension. Most of the cardiac anomalies, including right-sided aortic arch and right-to-left shunt, can be deduced from careful examination of the V/Q scan. A subsequent cardiac MRI scan confirmed the anomalies.

Altered myocardial motion pattern in Fabry patients assessed with CMR-tagging.

Progressive left ventricular hypertrophy is the hallmark of cardiac manifestations in patients with Fabry disease. Cardiovascular magnetic resonance with tissue tagging allows detailed assessment of the cardiac motion pattern. The aim was to test the hypothesis that not only Fabry patients with severe left ventricular hypertrophy exhibit changes in myocardial motion, but also Fabry patients with normal left ventricular mass. Magnetic resonance tagging using slice following complementary spatial modulation of magnetization (CSPAMM) combined with harmonic phase analysis (HARP) was applied to measure left ventricular shortening and contraction. Additionally, left ventricular rotation and global left ventricular torsion were examined. Twenty-nine Fabry patients grouped in patients with (n = 13) and without (n = 16) left ventricular hypertrophy were compared with 29 age and sex matched healthy volunteers. Long axis shortening and circumferential contraction showed reduced peak values with increasing left ventricular mass and were significantly reduced in Fabry patients with left ventricular hypertrophy (p < 0.001 and p < 0.05, respectively). Torsional deformation and apical rotation were increased both in Fabry patients with left ventricular hypertrophy as well as in patients with normal left ventricular mass (p < 0.001 for torsion) compared with controls. Applying the magnetic resonance tagging acquisition and analysis methods, myocardial motion abnormalities could not only be measured in Fabry patients with left ventricular hypertrophy but also in patients without macroscopic cardiac involvement.

Diagnosis of metastatic melanoma to the heart with an intrinsic contrast approach using melanin inversion recovery imaging.

Melanoma not infrequently metastasizes to the heart where it either remains occult or produces a very variable clinical picture. Recognition of metastatic lesions can be difficult on echocardiography because they are frequently intramural rather than intracavity. Magnetic resonance imaging with gadolinium contrast enhancement has previously been reported as the optimum method for identification of cardiac melanoma. This article presents an alternative approach that exploits the intrinsic paramagnetic properties of melanin to provide inherent contrast without the need for intravenous gadolinium injection. This approach is reported here in 3 patients with cardiac melanoma, and its accuracy is compared with a traditional gadolinium-enhanced method. We demonstrated that there were no significant differences among number, location, and volume of detected lesions using an inversion recovery sequence with or without intravenous gadolinium contrast.

Gradient-enhanced volume rendering: an image processing strategy to facilitate whole small bowel imaging with MRI.

MRI of the small bowel with positive contrast from orally administered contrast agent is a promising non-invasive imaging method. The aim of our study was to introduce small bowel MRI in a display format that clinicians are accustomed to and that maximizes the amount of information visualized on a single image. Twelve healthy volunteers, median age 32 years (range 18-49 years) participated in the study. A mixture of 20 ml Gd-DOTA (Dotarem), 0.8 g/kg body weight psyllium fibre (Metamucil) and 1.2 l water were sequentially administered over a period of 4 h. Imaging was performed on a 1.5 T unit (Philips Gyroscan, Intera). Fat-saturated, 3D, gradient echo imaging was performed while the patient was in apnea (30 s). Bowel motion was reduced with 40 mg intravenously administered scopolamine (Buscopan). A 3D, gradient-enhanced, volume rendering technique was applied to the 3D data sets. Standard projections [left anterior oblique (LAO), right anterior oblique (RAO), supine and prone] resembling conventional enteroclysis were successfully generated within fewer than 10 min processing time. Reconstructions were reproducible and provided an entire overview of the small bowel. In addition thin-slab volume rendering allowed an overlap-free display of individual structures. Positive contrast from orally administered contrast agent, combined with a gradient enhanced volume rendering method, allows the reconstruction of the small bowel in a pattern resembling conventional double-contrast enteroclysis. Segmental display without overlay is possible.

Small bowel motility assessment with magnetic resonance imaging.

PURPOSE: To assess primarily the feasibility of magnetic resonance imaging (MRI) as a tool to monitor small bowel peristaltic motion and secondarily to validate this technique by demonstrating drug-induced motility changes. MATERIALS AND METHODS: After a standardized oral preparation of Ispaghula husk (Metamucil) and meglumine gadoterate (Gd-DOTA; Dotarem), 10 volunteers underwent dynamic MRI using a two-dimensional turbofast field echo (TFE) sequence with a slice repetition time of 500 msec. Intraluminal cross-sectional caliber changes over time were assessed allowing quantification of the peristaltic frequencies and amplitudes of the small gut on various regions of interest. Pharmacologically induced alterations of the peristaltic motion after spasmolytics and gastrokinetic motion enhancers were investigated. RESULTS: Small bowel diameter measurement resulted in a peristalsis of 10.96 (SD = +/-2.51) waves per minute, oscillating regularly with mean amplitudes of 6.65 mm (SD = +/-1.15 mm). Peristaltic frequency in normal individuals is consistent with that observed with other techniques. Intravenous administration of scopolamine butylbromide (= hyoscine butylbromide/Buscopan) resulted in small bowel paralysis within 21.3 seconds (SD = +/-2.8 seconds). Prokinetic effect of intravenous metoclopramide (Paspertin) after Buscopan paralysis was tested in one volunteer, characterized by a slow recovery of peristalsis, which propagated from the proximal to the distal segments and enhanced contraction amplitudes. CONCLUSION: Dynamic MRI allows observing and quantifying small bowel peristalsis, characterizing motion patterns, and monitoring the effects of interfering factors such as drugs.